Advanced epithelial cancers, such as those of the prostate and breast, often exhibit morphologic and molecular changes characteristic of mesenchymal tissue. Breast cancer progression to an invasive metastatic state is hypothesized to represent a form of epithelial-mesenchymal transition (EMT), a process of profound importance during embryogenesis. A process referred to as “cadherin-switching” involves an increased expression of mesenchymal cadherins (often N-cadherin or cadherin-11) in conjunction with down-regulation of epithelial markers (E-cadherin), and is associated with both EMT and tumor progression. Cadherin-11, not normally expressed in normal epithelium, is found in prostate and breast cancer lymph node and bone metastases and its expression directly correlates to disease progression.